Update README.md

Author: svail-epri

README.md

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 # OpenADR-Virtual-End-Node
 This application is an implementation of a virtual end node (VEN) as defined in the OpenADR Alliance’s OpenADR 2.0 Profile B Specification (HTTP pull), updated July 1, 2013. OpenADR defines a machine-to-machine interface and includes the information model, transport and security mechanisms, and the manner in which data is exchanged between two end points. OpenADR 2.0 defines what and how information is communicated between an electricity service provider and customers, but it does not define how either end point uses the information. This VEN application is one example of how the specification can be applied. This open source application is written in C# and includes a graphical user interface.
 
-Developed to interact with an OpenADR 2.0 Virtual Top Node to provide users with insight into the OpenADR 2.0b specification, its information model, XML payloads, interactions with a VTN, etc. An EPRI’s Open Source VTN can be downloaded at: http://sourceforge.net/projects/openadr2vtn
+Developed to interact with an OpenADR 2.0 Virtual Top Node to provide users with insight into the OpenADR 2.0b specification, its information model, XML payloads, interactions with a VTN, etc. An EPRI’s Open Source VTN can be downloaded at: https://github.com/epri-dev/OpenADR-Virtual-Top-Node/releases